Fixed runtime example

lib/runtime/src/cache.rs

@@ -30,7 +30,8 @@ pub use wasmer_runtime_core::cache::{Artifact, Cache, WasmHash};
 ///     // Compute a key for a given WebAssembly binary
 ///     let key = WasmHash::generate(&[]);
 ///     // Store a module into the cache given a key
-///     fs_cache.store(key, module)?;
+///     fs_cache.store(key, module.clone())?;
+///     module
 /// }
 /// ```
 pub struct FileSystemCache {